Laparoscopic training system

ABSTRACT

A sensorized surgical instrument for training users laparoscopic surgical procedures is provided. The instrument includes at least one sensor selected from a group consisting of a strain gauge, accelerometer, magnetometer, and gyroscope. The sensor is attached directly to a handle of the instrument. A shaft assembly having a tool tip is interchangeably connectable to the handle. The sensor is connected to a computer configured to provide feedback useful to the user for improving the user&#39;s surgical skills. The feedback includes the time to complete a procedure, economy of motion, smoothness of motion and the force exerted at the tool tip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefit of U.S. ProvisionalPatent Application Ser. No. 62/458,972 entitled “Laparoscopic trainingsystem” filed on Feb. 14, 2017 and incorporated herein by reference inits entirety.

FIELD OF THE INVENTION

This application relates to surgical training, and in particular, tolaparoscopic training wherein a simulated torso is used to practicesurgical procedures and techniques and an evaluative system providesfeedback on the user's performance.

BACKGROUND OF THE INVENTION

Laparoscopic surgery requires several small incisions in the abdomen forthe insertion of trocars or small cylindrical tubes approximately 5 to10 millimeters in diameter through which surgical instruments and alaparoscope are placed into the abdominal cavity. The laparoscopeilluminates the surgical field and sends a magnified image from insidethe body to a video monitor giving the surgeon a close-up view of theorgans and tissues. The surgeon watches the live video feed and performsthe operation by manipulating the surgical instruments placed throughthe trocars.

Minimally invasive surgical techniques performed laparoscopically cangreatly improve patient outcomes because of greatly reduced trauma tothe body. There is, however, a steep learning curve associated withminimally invasive surgery, which necessitates a method of trainingsurgeons on these challenging techniques. There are a number oflaparoscopic simulators on the market, most of which consist of sometype of enclosure, and some type of barrier which can be pierced bysurgical instruments in order to gain access to the interior. Asimulated organ or practice station is placed inside the interior andsurgical techniques are practiced on the simulated organ or practicestation.

SUMMARY OF THE INVENTION

According to one aspect of the invention, an instrument for surgicaltraining is provided. The instrument includes a handle assembly and ashaft assembly. The handle assembly includes a movement arm having adistal end and a proximal end mechanically connected to a handle,trigger or other appropriate control mechanism. The shaft assembly isremovable and interchangeable with the handle assembly. The shaftassembly has a proximal end and a distal end and defines a lumentherebetween. The shaft assembly includes a tool element at the distalend and a rod having a proximal end and a distal end mechanicallyconnected to the tool element. The rod is located inside the lumen. Theproximal end of the shaft assembly is removably connectable to thehandle assembly such that the proximal end of the rod is connected tothe distal end of the movement arm. Actuation at the handle assemblymoves the movement arm and rod to operate the tool element. At least onesensor is attached directly to the handle assembly and configured toacquire and transmit at least one relational data of the instrument withrespect to a training environment during a training procedure. Acomputer system is connected to the at least one sensor and isconfigured to receive, store and process the data and to output at leastone feedback information to a user on a computer screen after thetraining procedure is completed.

According to another aspect of the invention, a method for surgicaltraining is provided. The method includes the step of providing at leastone surgical instrument having a handle assembly connected to aninterchangeable shaft assembly. The surgical instrument includes astrain gauge, an accelerometer, a gyroscope and a magnetometer alldirectly attached to the handle assembly, operably connected to acomputer, and configured to acquire at least one data. The methodincludes the step of providing a laparoscopic trainer and at least onesimulated tissue located inside the laparoscopic trainer. The methodincludes the step of providing to the user a group of predefinedsurgical procedures on the computer screen. The method includes the stepof selecting a predefined surgical procedure from the group ofpredefined surgical procedures. The method includes the step ofperforming the selected predefined surgical procedure by at least oneuser using the at least one surgical instrument upon the at least onesimulated tissue located inside the laparoscopic trainer. The methodincludes the step of collecting data from one or more of the straingauge, accelerometer, gyroscope, and magnetometer. The data is relatedto the selected predefined surgical procedure. The method includes thestep of calculating at least one information from the data. The methodincludes the step of providing on the computer screen the at least oneinformation and/or data to the user upon completion of the selectedpredefined surgical procedure. The at least one information and/or datais based on data collected for the at least one user.

According to another aspect of the invention, a laparoscopic trainer isprovided. The trainer includes a bottom, at least one sidewallencompassing the bottom and a penetrable simulated abdominal walldefining at least a portion of a top of the trainer. The top is spacedapart from the bottom to define an interior bounded by the at least onesidewall. The at least one sidewall includes a door configured to openand close to provide access to the interior. The door has an apertureextending from the outside of the trainer to the interior to provideaccess to the interior via the aperture and an interchangeable adapterextending between the top and bottom and fixedly yet removably connectedto the trainer in the location of the aperture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a surgical training device according tothe present invention.

FIG. 2 is a perspective view of a surgical training device according tothe present invention.

FIG. 3 is a perspective view of a surgical training device according tothe present invention.

FIG. 4 is a side view of someone performing a simulated procedure in alaparoscopic trainer.

FIG. 5 is a top perspective view of a surface curved in one directiononly.

FIG. 6 is a top perspective view of a surface curved in two directions.

FIG. 7 is a top perspective, exploded view of a negative cavity vacuummold according to the present invention.

FIG. 8 is a top perspective, exploded section view of a negative cavityvacuum mold according to the present invention.

FIG. 9 is a top perspective, section view of a negative cavity vacuummold according to the present invention.

FIG. 10 is a top perspective, exploded section view of a frame, piece offoam and vacuum mold according to the present invention.

FIG. 11A is a top perspective view of a piece of foam in place on avacuum mold according to the present invention.

FIG. 11B is a top perspective view of a piece of foam formed on a vacuummold according to the present invention.

FIG. 12 is a top perspective, exploded section view of a frame, unformedlayer, formed layers and vacuum mold according to the present invention.

FIG. 13A is a top perspective, section view of a piece of foam in placeon a vacuum before forming according to the present invention.

FIG. 13B is a top perspective, section view of layers of foam on avacuum mold after forming according to the present invention.

FIG. 14 is a top perspective, exploded section view of a frame, a layerof foam before forming, a plurality of foam layers after forming and avacuum mold according to the present invention.

FIG. 15A is a top perspective, section view of a frame, a layer of foambefore forming, a plurality of foam layers after forming and a vacuummold according to the present invention.

FIG. 15B is a top perspective, section view of a frame and a pluralityof foam layers after forming and a vacuum mold according to the presentinvention.

FIG. 16 is a top perspective view of a foam layer and an uncured sheetof silicone to make an artificial skin layer according to the presentinvention.

FIG. 17A is a top perspective view of a foam layer in place on a layerof silicone to form an artificial skin layer according to the presentinvention.

FIG. 17B is a top perspective view of a foam layer adhered to a trimmedlayer of silicone forming an artificial skin layer according to thepresent invention.

FIG. 18 is a top perspective, exploded section view of a weighted plug,a plurality of adhered foam layers after forming, a frame, a flatartificial skin layer and a the vacuum mold according to the presentinvention.

FIG. 19A is a top perspective, exploded section view of a weighted plug,a plurality of adhered foam layers after forming, and a skin layerbefore forming in place under a frame on a vacuum mold according to thepresent invention.

FIG. 19B is a top perspective, exploded section view of a weighted plug,a plurality of adhered foam layers after forming, and a skin layer afterforming in place under a frame and on a vacuum mold according to thepresent invention.

FIG. 19C is a top perspective, exploded section view of a weighted plug,a plurality of adhered foam layers after forming, and a skin layer afterforming in place under a frame and on a vacuum mold according to thepresent invention.

FIG. 19D is a top perspective, section view of a weighted plug, aplurality of adhered foam layers after forming, and a skin layer afterforming in place under a frame and on a vacuum mold according to thepresent invention.

FIG. 20A is a top perspective view of a simulated abdominal wallaccording to the present invention.

FIG. 20B is a bottom perspective view of a simulated abdominal wallaccording to the present invention.

FIG. 21 is a top perspective view of a simulated abdominal wall andframe according to the present invention.

FIG. 22 is a top perspective, exploded view of a simulated abdominalwall between two frame halves according to the present invention.

FIG. 23 is a perspective, section view of a simulated abdominal and twoframe halves showing an angled channel.

FIG. 24A is a top perspective, section view of a bottom frame halfshowing retention protrusions according to the present invention.

FIG. 24B is a cross-sectional view of a simulated abdominal wall andframe according to the present invention.

FIG. 25 is a side elevational view of a typical laparoscopic surgicalprocedure performed in a simulator according to the present invention.

FIG. 26A is a side elevational view of a laparoscopic grasper instrumentaccording to the present invention

FIG. 26B is a side elevational view of a laparoscopic scissor instrumentaccording to the present invention.

FIG. 26C is a side elevational view of a laparoscopic dissectorinstrument according to the present invention.

FIG. 27 is a side elevational view of a laparoscopic dissectorinstrument shaft detached from a handle according to the presentinvention.

FIG. 28 is a schematic of a laparoscopic trainer containing artificialorgans and two laparoscopic surgical instruments connected to anexternal microprocessor during use according to the present invention.

FIG. 29 is a top view of a circuit board according to the presentinvention.

FIG. 30 is an electrical schematic of a strain gauge configurationaccording to the present invention.

FIG. 31A is a side elevational, section view of an instrument handleassembly and shaft assembly according to the present invention.

FIG. 31B is an end view of a movement arm and section of a rod of asurgical instrument according to the present invention.

FIG. 31C is a top, section view of a movement arm and rod of a surgicalinstrument according to the present invention.

FIG. 31D is an end view of a movement arm and section of a rod of asurgical instrument according to the present invention.

FIG. 31E is a top, section view of a movement arm and rod of a surgicalinstrument according to the present invention.

FIG. 32 is a top perspective view of a laparoscopic surgical instrument,trocar and simulated organs inside a laparoscopic trainer according tothe present invention.

FIG. 33 is a side elevational view of a laparoscopic instrument havingan inertial motion unit on a handle assembly according to the presentinvention.

FIG. 34 is a flow chart of steps taken by a system according to thepresent invention.

FIG. 35 is a schematic of an accelerometer calibration method andequations for all axes in both positive and negative directionsaccording to the present invention.

FIG. 36 is a schematic of a magnetometer calibration model according tothe present invention.

FIG. 37 is a strain gauge calibration plot of measured voltage againstactual force measured by a load cell for calibration according to thepresent invention.

FIG. 38 illustrates a trimming and segmentation method for calculatingthe timing according to the present invention.

FIG. 39 is a flow chart of data in a MARG algorithm, an IMU orientationestimation algorithm according to the present invention.

FIG. 40 illustrates a smoothness algorithm and an equation used forcurvature calculations according to the present invention.

FIG. 41 is a schematic illustrating an economy of motion algorithm andequation according to the present invention.

FIG. 42 is a computer screen shot view of a user interface starting pageaccording to the present invention.

FIG. 43A is a computer screen shot view of a user interface calibrationscreen according to the present invention.

FIG. 43B is a computer screen shot view of a user interface calibrationscreen according to the present invention.

FIG. 43C is a computer screen shot view of a user interface calibrationscreen according to the present invention.

FIG. 43D is a computer screen shot view of a user interface calibrationscreen according to the present invention

FIG. 44 is a computer screen shot view of a user interface lessonselection screen according to the present invention.

FIG. 45 is a computer screen shot view of a user interface previewscreen according to the present invention.

FIG. 46 is a computer screen shot view of a user interface questionnairescreen according to the present invention.

FIG. 47 is a computer screen shot view of a user interface learningmodule screen according to the present invention.

FIG. 48 is a computer screen shot view of a user interface user feedbackscreen according to the present invention.

FIG. 49 is a flowchart illustrating the path of data flow according tothe present invention.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to FIGS. 1-3, there is shown a surgical training device 10that allows a trainee to practice intricate surgical maneuvers in anenvironment that is safe and inexpensive. The device 10 is generallyconfigured to mimic the torso of a patient, specifically the abdominalregion. The surgical training device 10 provides an enclosure forsimulating a body cavity 12 that is substantially obscured from theuser. The cavity 12 is sized and configured for receiving simulated orlive tissue or model organs or skill training models and the like. Thebody cavity 12 and the enclosed simulated organs and/or models areaccessed via a penetrable tissue simulation region 14 that is penetratedby the user employing devices such as trocars to practice surgicaltechniques and procedures using real surgical instruments such as butnot limited to graspers, dissectors, scissors and energy-based fusionand cutting devices on the simulated tissue or models found located inthe body cavity 12. The surgical training device 10 is particularly wellsuited for practicing laparoscopic or other minimally invasive surgicalprocedures.

Still referencing FIG. 1, the surgical training device 10 includes a topcover 16 connected to and spaced apart from a base 18. The top cover 16includes an integrally formed depending portion and the base 18 includesan upwardly extending portion both of which cooperate to form thesidewalls and backwall of the surgical training device 10. The surgicaltraining device 10 includes a frontwall 20 that is hinged to the base 18to form a door that opens to the cavity 12. The frontwall 20 includes afront opening 22 that provides lateral, side access to the cavity 12which is useful for practicing vaginal hysterectomies and transanalprocedures. The frontwall 20 is shown in a closed position in FIG. 1 andin an open position in FIGS. 2-3. A latch 24 is provided and configuredto release the tissue simulation region 14 from the top cover 16.Another release button is configured to open the door. The tissuesimulation region 14 is representative of the anterior surface of thepatient and the cavity 12 between the top cover 16 and the base 18 isrepresentative of an interior abdominal region of the patient whereorgans reside. The top cover 16 includes an opening that is configuredto receive the tissue simulation region 14. The tissue simulation region14 is convex from the outside to simulate an insufflated abdomen. Thetissue simulation region 14 includes numerous layers representingmuscle, fat and other layers as described in U.S. Pat. No. 8,764,452issued to Applied Medical Resources Corporation and incorporated hereinby reference in its entirety. The tissue simulation region 14 will bedescribed in greater detail below. The base 18 includes rails 26 shownin FIG. 3 that extend upwardly from the bottom surface inside the cavity12. The rails 26 are configured to receive a tray (not shown) thatcarries simulated or live tissue. The tray is useful for an arrangementcomprising a plurality of organs and/or retaining fluid or simulatedorgans made of hydrogel and the like. The tray is placed through thefront opening and onto the rails upon which it can then slide into thecavity 12. The tray includes a base on which artificial organs aresupported. This base is located above the bottom floor of thelaparoscopic trainer. A customized tray having a certain depth allowsthe height of the organs to be adjusted with respect to the rails byselecting the appropriate depth tray according to the demands ofselected surgical procedure. The rails advantageously permit deepertrays to carry more artificial organs or to customize the distancebetween the top of the artificial organs and the simulated abdominalwall. A shorter distance such as provided by a shallower tray provides asmaller working space for surgical instruments and may increase thedifficulty and/or increase the realism of the procedure. Hence, therails permit a second platform for artificial organs other than thebottom floor of the trainer which is considered as the first platformfor artificial organs. The second platform is adjustable byinterchanging trays placing the artificial organs therein and slidingthe tray onto the rails 26. Lights such as a strip of light emittingdiodes (LEDs), sensors and video cameras all generally designated byreference number 28 may also be provided within the cavity 12. Thesurgical training device 10 is also provided with a removable adapter30. The adapter 30 extends between and connects with the top cover 16and base 18. The adapter 30 includes an aperture 32 that is cylindricalin shape and is sized and configured for connecting with a simulatedorgan such as a simulated vagina or colon and particularly useful forpracticing lateral access procedures including but not limited tovaginal hysterectomies and transanal procedures. When a lumen-shapedartificial organ is connected to the adapter the aperture 32 is incommunication with the lumen interior. The opening 22 in the frontwall20 is also in communication with the lumen interior providing accessinto the lumen from outside the trainer. The adapter 30 connects toprongs in both the top cover 16 and the base 18. When connected, theaperture of the adapter 30 aligns with the opening 22 in the frontwall20 and is located behind the frontwall 20. The backside of the frontwall20 may include a recess sized and configured to receive the adapter 30making it substantially flush with the front side of the frontwall 20.The frontwall 20 when closed and locked also aids in keeping the adaptersecure especially when a procedure requires significant force to beapplied on the artificial organ. The adapter 30 is interchangeable withan adapter that does not have an aperture 32 and is blank such that,when it is connected to the surgical training device, the opening 22 inthe frontwall 20 is covered and light is not permitted to enter thecavity. The blank adapter is employed when the simulation does notrequire lateral access to the cavity. The base 18 further includesheight adjustable legs 34 to accommodate common patient positioning,patient height and angles. In one variation, the legs 34 are made ofsoft silicone molded around hardware. The hardware includes a cap screw,tee nut and a spacer. The spacer made of nylon provides a hard stop thatcontacts the bottom of the base once the legs are screwed in so thateach leg is the same length. The tee nut is used to grip the siliconefoot to prevent it from spinning independently from the cap screw. Thedistal end of each of the legs is provided with silicone molded foot.The silicone feet are semi-spherical and allow the unit to self-leveland dampen vibrations because of the soft silicone composition.

The surgical training device 10 has an elegant and simple design withthe ability to simulate different body types such as patients with highbody mass index. The trainer 10 can be used by one or more people at thesame time and has a large area in the tissue simulation region toaccommodate trocar/port placement for a variety of common procedures.The device 10 is configured to resemble a pre-insufflated abdomen and,therefore, more anatomically accurate than other trainers that aresimply box-like or do not have large tissue simulation regions curved tosimulated an insufflated abdomen. The interior cavity 12 is configuredto receive a tray that can slide on the rails 26 into the cavity 12 suchthat moist/wet live or simulated organs made of hydrogel material can beutilized in the practice of electrosurgical techniques. The rails 26also advantageously permit the floor of the inserted tray to be closerto the tissue simulation region reducing the vertical distancetherebetween. The device 10 is also conveniently portable by one person.

The surgical trainer 10 is a useful tool for teaching, practicing anddemonstrating various surgical procedures and their related instrumentsin simulation of a patient undergoing a surgical procedure. Surgicalinstruments are inserted into the cavity 12 through the tissuesimulation region 14. Various tools and techniques may be used topenetrate the top cover 16 to perform mock procedures on simulatedorgans or practice models placed between the top cover 16 and the base18. An external video display monitor connectable to a variety of visualsystems for delivering an image to the monitor may be provided. Forexample, a laparoscope inserted through the tissue simulation region 14connected to a video monitor or computer can be used to observe recordand analyze the simulated procedure. The surgical instruments used inthe procedure may also be sensorized and connected to a computer. Also,video recording is provided via the laparoscope to record the simulatedprocedure.

There are a number of ways that the tissue simulation region can bemade. One exemplary variation is the tissue simulation region beingsimulated as an abdominal wall. Previous versions have used layers ofdifferent types of flat foam and/or silicone sheets to simulate the lookand/or feel of the different types of tissue present in the humanabdominal wall. The sheets simulating an abdominal wall are curved inone or more direction.

One problem with previous versions is that the simulated abdominal wallrequires some type of support structure to prevent collapse or bucklingof the simulated abdominal wall during use. The support structureholding the simulated abdominal wall generally detracts from the overallfeel and visual effect of the simulated abdominal wall, and often getsin the way during simulated procedures, especially during trocarplacement.

An aesthetic shortcoming of this type of simulated abdominal wall isthat the foam can only be made to curve in one direction, which greatlydetracts from its realism. An actual insufflated abdomen curves inmultiple directions, and it is a goal of the present invention to createa more lifelike simulation.

An abdominal wall with realistic curvature and landmarks is desirablefor the training of proper port placement. Proper port placement allowssafe access to the abdominal cavity and adequate triangulation foraccessing the key anatomical structures throughout a simulated surgicalprocedure.

The simulated abdominal wall for use with the surgical training device10 and its method of manufacture will now be described in greaterdetail. The simulated abdominal wall is a layered foam abdominal wallthat has no need for additional internal or external support structures,and has the visual appeal of a truly convex surface with appropriatelandmarks. The method of making the simulated abdominal wall involveslaminating multiple layers of foam with the use of adhesive. As eachsubsequent layer of foam is added, the overall structure becomes morerigid. After several layers have been added, the simulated abdominalwall will tend to spring back to its original shape, even after beingseverely deformed, and retain enough rigidity to allow realisticpuncture by trocars. The simulated abdominal wall has the convex visualappearance of an insufflated human abdomen. Also, the simulatedabdominal wall of the present invention allows the user to place atrocar anywhere through its surface without interference fromunrealistic underlying support structures. The simulated abdominal wallcan withstand repeated use. Previous simulated abdomens have arubber-like skin layer that is not bonded to the supporting foammaterials, resulting in a simulated abdominal wall that appears wornonly after one or two uses. A skin layer comprised of siliconemechanically bonded to an underlying foam layer has been created andintegrated into the simulated abdominal wall. Because the silicone issecurely bonded to the underlying foam, a much more durable skin layeris realized, and costs are driven down by reducing the frequency ofabdominal wall replacement. Furthermore, in previous versions where theouter skin layer is not bound to the underlying layers, unrealisticspaces open up between the simulated abdominal wall layers during portplacement. The present invention eliminates this issue. A method hasbeen developed to give shape to the simulated abdominal wall. Thismethod meets the aforementioned goals, and is described in reference tothe figures.

The method involves the use of a vacuum mold to form and join convexfoam sheets. In the process, a foam sheet is placed on the vacuum moldand held in place with a frame. The vacuum pump is then turned on, andheat is applied to the foam. The heat relaxes the foam, allowing it toyield and stretch into and conform to the shape of the mold cavity dueto the suction of the vacuum. Spray adhesive is applied to the foam inthe mold and/or to a new sheet of foam. Next, a multitude of holes arepoked through the first layer of foam so that the vacuum can act on thesecond layer of foam through the first. The order of hole-poking andglue application can be reversed and the process will still work. Theframe is removed, the next sheet of foam is placed glue side down ontothe vacuum mold (with the first foam layer still in place, glue sideup), and the frame is replaced. Again, the vacuum pump is turned on andheat is applied to the top foam layer. As the two foam layers come intocontact they are bonded together. This process is then repeated for eachdesired foam layer. With the addition of each foam layer, the simulatedabdominal wall gains strength.

Once the desired foam layer configuration is completed, the simulatedabdominal wall is then inserted into the abdominal wall frame. Theabdominal wall frame is a two-piece component that secures the simulatedabdominal wall around the perimeter by compressing it between the topand bottom frame parts, and allows the user to easily install and removethe wall from the surgical simulator enclosure. The geometry of theabdominal wall frame adds further support to the convex form and feel ofthe simulated abdominal wall by utilizing an angled channel along theperimeter that the simulated abdominal wall is compressed between.

The method described hereinbelow relies on a bent lamination mechanismformed, in part, by successively gluing surfaces together that have beenmade to curve. A structure that maintains the desired curvature emergeswith each additional layer.

The method uses vacuum forming to achieve curved surfaces. In thissecond method, flat sheets of foam are placed over a negative cavityvacuum mold, a frame is placed over the foam to make an air-tight seal,and the vacuum mold is evacuated. As the vacuum is pulled, heat isapplied to the foam, which allows the foam to yield and stretch into themold cavity. When a new layer is to be added, a multitude of holes arepoked through the previously formed foam layers. Adhesive is appliedbetween the layers so that they form a bond across the entire curvedsurface.

After several layers of foam have been laminated together, thework-piece begins to maintain the curved shape of the mold. By adding orremoving layers, the tactile response of the foam layers can be tailoredfor more lifelike feel.

Once the desired foam layer configuration is completed, the simulatedabdominal wall is then inserted into the abdominal wall frame, which isa two-piece system consisting of a top and bottom frame that secures thesimulated abdominal wall along the perimeter by compressing the foamlayers in an angled channel created by the top and bottom framecomponents in a friction-fit or compression fit engagement or the like.The design of the frame allows the user to easily install and remove theframe from the surgical simulator enclosure by snapping the perimeter ofthe frame to the surgical simulator enclosure. The geometry of theabdominal wall frame adds further support to the convex form of thesimulated abdominal wall by utilizing an angled channel along theperimeter that the simulated abdominal wall is compressed between. Theangled channel of the frame follows the natural shape of the simulatedabdominal wall. Simply compressing the simulated abdominal wall betweentwo flat frame pieces results in significantly increased support for theconvex form and produces a realistic feel of the simulated abdominalwall and advantageously prevents unwanted inversion of the simulatedabdominal wall during normal use.

With reference to FIG. 4, a surgical training device also called atrainer or surgical simulator 10 for laparoscopic procedures is shownthat allows a trainee to practice intricate surgical maneuvers in anenvironment that is safe and inexpensive. These simulators 10 generallyconsist of an enclosure 111 comprising an illuminated environment asdescribed above that can be accessed through surgical access devicescommonly referred to as trocars 112. The enclosure is sized andconfigured to replicate a surgical environment. For instance, thesimulator may appear to be an insufflated abdominal cavity and maycontain simulated organs 113 capable of being manipulated and “operatedon” using real surgical instruments 114, such as but not limited tograspers, dissectors, scissors and even energy-based fusion and cuttingdevices. Additionally, the enclosure 10 may contain a simulatedabdominal wall 115 to improve the realism of the simulation. Thesimulated abdominal wall 115 facilitates the practice of first entry andtrocar 112 placement and advantageously provides a realistic tactilefeel for the instruments moving through the simulated abdominal wall.

Turning to FIG. 5, a surface 116 curved in one direction is shown. Manyof the current products on the market make use of a simulated abdominalwall that curves in only one direction as shown in FIG. 5. This shape isan approximation of the real shape of an insufflated abdomen that iscurved in several directions. Furthermore, a simulated abdominal wallcurved in one direction as shown in FIG. 5 is not as structurally soundas a shape that curves in two directions. Simulated abdominal walldesigns that are curved in only one direction often necessitate the useof additional internal support structures beyond a perimeter frame suchas crisscrossing reinforcing spine or buttress. FIG. 6 shows a surface116 that curves in two directions which is more realistic and also morestructurally sound than a surface that curves in only one direction. Thesimulated abdominal wall 14 of the present invention is curved in twodirections as shown in FIG. 6.

In view of the foregoing, the present invention aims to eliminate theneed for internal support structures while creating a shape that has avisual look and tactile feel that more closely mimic the real abdominalwall.

Turning now to FIG. 7, an exploded view of a negative cavity vacuum moldis shown, consisting of a base 123, air outlet 124, frame 125, and mainbody 126. FIG. 8 shows an exploded section view of the same vacuum mold.In this view, air-holes 127 are seen to pierce the cavity 128. FIG. 9shows an assembled section view of the vacuum mold, showing the plenum129 created between the base 123 and main body 126, the frame seal 130between the base 123 and main body 126, as well as the plenum seal 131between the main body 126 and frame 125.

Looking now to FIG. 10, the vacuum mold is shown with a foam sheet 132ready to be placed on the main body 126, and held in place with frame125. FIG. 11A shows the flat foam sheet 132 prior to forming locatedinside the main body and covered by the frame 125. FIG. 11B shows theformed foam sheet 133 after application of vacuum across the plenum.During the forming process, air is evacuated through outlet 124, whichcreates negative pressure in the plenum 129. This negative pressure actsthrough air holes 127, and sucks the flat foam sheet 132 towards theinner surface of the cavity 128. While air is being evacuated throughoutlet 24, heat is applied to the top of the foam, which allows the foamto stretch and make complete contact with the surface of the cavity.

FIG. 12 shows an exploded section view of a foam layer 132 being addedto the work-piece. Prior to forming in the vacuum mold, a multitude ofholes 142 must be poked through the formed foam layer 133 to allow thesuction to act through its thickness, thus pulling the flat foam sheet132 into the cavity. Also prior to placement in the vacuum mold,adhesive must be applied to the top side of the formed foam layer 133,as well as to the underside of the flat foam sheet 132. FIGS. 13A-13Bshow the flat foam sheet 132 being simultaneously formed and laminatedto the formed foam sheet 133, and thus beginning to form the pre-madefoam layers 134. Again, different types and colors of foam may be usedto simulate the colors and textures present in a real abdominal wall.

An exploded view of this process is shown after several repetitions inFIG. 14, where a flat foam sheet 132 will be pressed against a pluralityof pre-made foam layers 134 using frame 125. FIG. 15A shows a collapsedview of the aforementioned setup before and, in FIG. 15B, after vacuumforming. Again, between adding layers, it is essential to poke aplurality of small holes 142 through the pre-made foam layers 134, aswell as to apply adhesive to the top of the pre-made foam layers 134 andto the underside of the next flat foam layer 132.

Turning now to FIG. 16, an exploded view of the skin layer is observed,showing skin foam layer 137, and uncured silicone layer 138. FIG. 17Ashows the skin foam layer 137 in place on the uncured silicone layer138. When the silicone cures on the foam, it creates a mechanical bondwith the slightly porous foam material. Once the silicone is fullycured, the excess is trimmed resulting in the trimmed skin layer 139shown in FIG. 17B.

FIG. 18 shows an exploded view of the vacuum mold main body 126, thetrimmed skin layer 139 with the silicone side facing the main body 126,the frame 125, the pre-made foam layers 134 and a weighted plug 140 usedto press the layers together. FIG. 19A shows the trimmed skin layer 139held in place on the vacuum mold's main body 126 by the frame 125, priorto evacuation of air in the mold. FIG. 19B shows the trimmed skin layer139 pulled into the cavity of the vacuum mold, with the pre-made foamlayers 134 with or without adhesive applied and ready to be pressed downinto the cavity by the weighted plug 140. FIG. 19C shows the pre-madefoam inserts 134 placed into the cavity on top of the trimmed skin layer139. FIG. 19D shows the final step of the process, the placement of theweighted plug 140 on top of the pre-made foam insert 134.

FIGS. 20A and 20B show right side up and upside down section views ofthe final simulated abdominal wall 141 in its finished state, prior tohaving its edges bound by the simulated abdominal wall frame top andbottom halves 143, 144. The simulated abdominal wall 141 isapproximately 12-15 centimeters wide by approximately 15-18 centimeterslong and the area of the domed simulated abdominal wall is betweenapproximately 250-280 square inches. The large area permits not onlymultiple trocar ports to be placed, but also, they can be placedanywhere on the simulated abdominal wall. The simulated abdominal wallis also interchangeable with other simulated abdominal walls includingones configured for obese and pediatric patients. Furthermore, the largesimulated abdominal wall is not limited to practicing laparoscopic,minimally invasive procedures, but also, advantageously permits openprocedures to be performed through the simulated abdominal wall.

FIG. 21 shows the simulated abdominal wall 141 set into the simulatedabdominal wall frame 143, 144. This unit is then fixed into alaparoscopic trainer. FIG. 22 shows the exploded view of the simulatedabdominal wall 141 and frame assembly which includes a top frame 143,and a bottom frame 144. The top frame 143 and bottom frame 144 can beassembled together via screws in the case of a re-usable frame system,or snapped together via heat staking or other low-cost assembly method.

With reference to FIG. 23, one of the key features in the simulatedabdominal wall frame 145 is the angled channel 146 in which thesimulated abdominal wall 141 is compressed. The angle of the channel 146follows the contour of the simulated abdominal wall 141 andsignificantly increases the support and form of the convex simulatedabdominal wall 141. In contrast, a simulated abdominal wall 141 that iscompressed and retained between two flat frames is relatively weaker andmore likely to invert/collapse during use.

FIG. 24A shows the protrusions 147 that are spaced around the perimeterof the bottom frame 144. These retaining protrusions 147 can also bepresent on the top frame 143, or both frame halves 143, 144. Theseretaining protrusions 147 provide additional retention of the simulatedabdominal wall 141 within the simulated abdominal wall frame 145 bypressing or biting into the simulated abdominal wall as it is compressedbetween the frame top 143 and frame bottom 144. With reference to FIG.24B, a simulated abdominal wall 141 is compressed between the two framehalves 143, 144 and is pierced by a retaining protrusion 147.

It should be noted that although one method is described here forlayering pre-made foam sheets in order to create a curved surface withstructural integrity, other methods are also within the scope of thepresent invention, including a casting mold that allows the user tosequentially build up a multitude of curved layers that are adhered toone another across their entire surface.

After the surgical training device 10 is assembled with the simulatedabdominal instrument in place atop the trainer, laparoscopic orendoscopic instruments are used to perform mock surgeries using thesurgical training device 10 of the present invention. Generally,artificial tissue structures and organs sized and configured torepresent actual anatomical features, skill-specific models or one ormore skill practice stations are placed inside the trainer 10. Surgicalsimulators, such as the surgical training device 10 of the presentinvention, are especially useful when they include feedback for theuser. In the mock procedure, the performance of the user is monitored,recorded and interpreted in the form of user feedback throughintegration of various sensing technologies into the simulatedenvironment. The present invention provides low-cost sensorizedinstruments that are capable of monitoring the motion and force appliedby a user to the simulated tissue and the like located inside thetrainer cavity. The sensorized instruments are connected to amicroprocessor, memory and video display and configured to receive datafrom various sensors including but not limited to sensors located on thesurgical instruments, analyze the data and provide appropriate feedbackto assist in teaching and training the user. The present invention canbe employed with multiple surgical instruments and accessories,including but not limited to graspers, dissectors, scissors, and needledrivers. Data gathered from a mock surgery can be used to compare atrainee's performance to that of an experienced surgeon or that of othertrainees to provide appropriate feedback. Such a system may improve therate of skill acquisition of trainees and, as a result, improve surgicaloutcomes, and skills.

The present invention utilizes a number of sensing systems making use ofa variety of fundamental sensing principles and technologies such asstrain gauges. For example, a strain gauge commonly consists of ametallic foil pattern supported by a flexible backing. When appliedproperly to a structure of interest, stresses and strains experienced bythe structure are transferred to the strain gauge as tension,compression or torsion on the metallic foil pattern. These mechanicalstimuli alter the geometry of the foil pattern and, as a result, cause achange in the electrical resistance of the foil pattern, which can bemeasured. An additional aspect that is important to the use of straingauges is the configuration in which they are utilized. Strain gaugesare typically wired into an electrical circuit, commonly known as theWheatstone bridge, which consists of two parallel voltage dividers. Inthis configuration, the difference between the electric nodes at thecenter of the voltage dividers of the circuit is amplified and measured.The configuration in which the strain gauges are both wired into thecircuit and applied to an object of interest determines what loads thesensor system actually measures. For example, to measure axial strain,two strain gauges are aligned on opposite sides of a component and arealso wired on opposite sides of the bridge circuit such that they do notshare a node.

Turning now to FIG. 25, surgical simulators 10 for laparoscopicprocedures have been developed that allow a trainee to practiceintricate surgical maneuvers in an environment that is safe andinexpensive. These simulators generally consist of a cavity 12comprising an illuminated environment that can be accessed throughsurgical access devices commonly referred to as trocars 212 and 213. Theenclosure is sized and configured to replicate a surgical environment,such as an insufflated abdominal cavity containing simulated organs 214that are capable of being manipulated and “operated on” using realsurgical instruments 216 and 217, such as but not limited to graspers,dissectors, scissors and even energy-based fusion and cutting devices.Laparoscopes/endoscopes or other cameras 215 are inserted into thecavity through the simulated abdominal wall. More advanced simulatorsmay also make use of various sensors to record the user's performanceand provide feedback. These advanced systems may record a variety ofparameters, herein referred to as metrics, including but not limited tomotion path length, smoothness of motion, economy of movement, force,etc.

In view of the forgoing, the present invention aims to monitor forceapplied by a trainee, interpret the collected information and use it toimprove user performance through feedback and appropriate teaching. Thepresent invention itself focuses on the methods for monitoring andcollecting force applied by the user.

In reference to FIGS. 26A, 26B, and 26C, a variety of laparoscopicinstruments are shown including a grasper 218, a dissector 219 andscissors 220, respectively. These devices, although different infunction, generally share certain key features. Each instrument includesa handle 221 which controls the operable distal end of the instrument.Actuation of the handle opens and closes the jaw-like tip to performgrasping, dissecting or cutting based on the type of instrument used.Additionally, the instrument is configured to permit rotation of theshaft 227 by way of an adjustable component 222 in reach of the user'sfingers. A locking mechanism 223 is also provided at the handle to allowthe surgeon/trainee to maintain the jaws of the instrument at a givenposition.

With further reference to FIG. 27, the present invention makes use of ascissor type handle 221 that can be reused after each surgicalprocedure. The handle 221 is designed such that a variety of disposableshafts 227, each with a different tip element 218-220, can be fixed tothe same handle 221. In the present system, the disposable shafts 227have a ball end 229 connected to a rod 230 which articulates with theinstrument's tips 218. This piece fits into a spherical slot 231 at theend of a movement arm 232 inside of the handle 221 that connects to thegrips 225 and 226. Movement of the thumb grip 225 actuates the rod 232which opens or closes the instrument tips 218. The ability of such asystem to swap out shafts 227 advantageously permits a single handle 221to house the necessary electronics while being interchangeable with avariety of different instrument shafts and tips.

As shown in FIG. 28, the electronics such as the circuit board andsensors for force sensing are enclosed in a housing 240 and connected tothe handle 221 of the instrument. The electronics are electronicallyconnected via a USB cord 238, 242 to an external computer 239. Thefollowing descriptions reference a reposable system 221. Previously theinstruments with sensors located on the shaft were disposable and verydifficult to sterilize if needed. However, with the sensors on thehandle, the shaft assembly can be interchanged and discarded as needed.The reposable handle 221 is modified to incorporate housing 240 for acustom circuit board 241.

The circuit board 241 is shown in FIG. 29. The board 241 includessensors 244, microprocessor 247 and a communication port 242 configuredfor communication with an external computer 239. The board 241 includesa 9-degree-of-freedom inertial measurement unit (9-DOF IMU) 244 and ahigh-resolution analog-to-digital converter (ADC) 243. The IMU 244 iscomprised of a 3-axis accelerometer, 3-axis gyroscope, and 3-axismagnetometer. There are electrostatic discharge (ESD) diodes locatedbetween the ADC and ground to prevent electrical failure when the deviceis exposed to an electrical shock. When utilized together along withappropriate calculations, information regarding the user's movement canbe determined.

The ADC 243 compares the voltages of the strain gauge bridge circuitseen in FIG. 30. As can be seen in FIG. 30, the strain gauges 313 and314 are configured such that axially applied loads stress the gauges 313and 314 resulting in a change in resistance between the gauges and theaccompanying resistors 315 and 316 which form each node 317 and 318.Each strain gauge is connected to a resistor 315 and 316 such that thischange in resistance results in a measurable difference between theresistive components forming each node 317 and 318 and, as a result, thevoltage 319 measured between the nodes 317 and 318. The ADC 243 measuresthis difference and, through the use of appropriate calculations, theforce applied at the instrument tip can be determined. In regards tocommunication with an external computer, as can be seen in FIG. 28, theboard 241 located inside the housing 240 is connected to an externalcomputer 239 and powered by way of a micro-USB type 2.0 connector 238,242.

Turning now to FIG. 31A, force sensing technologies coupled to thehandle 221 that make use of strain gauges 255 are provided. The presentinvention positions the strain gauges 255 on the movement arm 232 insidethe handle 221. Wires 256 connected to the strain gauges pass throughthe handle 221 to the circuit board 241 inside the housing 240. It isworth noting that the present invention places the strain gauges on themovement arm in a half-bridge configuration. With the strain gauge onthe handle assembly, the longevity of the instrument is increasedbecause when the shaft is interchanged with the handle there are nostresses placed on the gauge and connecting wires. During interchangingof the shaft, the wires remain advantageously concealed and protectedinside handle assembly and are not exposed or stretched inadvertently aswould be the case if the sensors were placed on the shaft. Placement ofthe sensors in the handle assembly advantageously allows for shorterwires. However, moving parts inside the handle may rub and wear out thewires. Accordingly, the wires are coated in polyetheretherketone (PEEK)to protect and prevent wear from abrasion encountered inside the handle.The small gauge of the wires and the PEEK coating prevent the lead wiresfrom wearing and provide a longer lifetime and more accurate data.

As can be seen in FIG. 31B-31C, strain gauges 255 are applied onopposite sides of the movement arm 232 such that a half-bridge may beformed by connecting the strain gauges 255 in the appropriate manner. Inthis fashion, applied force is monitored as a function of the axialdeformation of the movement arm 232 during use. The sensitivity of thissensing setup is controllable, in part, by changing the material thatthe movement arm 232 is made of. A larger sensing range is implementedby making the movement arm 232 out of materials with low elastic modulisuch as hardened steel. On the other hand, use of materials with higherelastic moduli, such as aluminum, result in a lower overall sensingrange and a higher sensitivity as the movement arm 232, and as a resultthe strain gauges 255, deform more under axially loading. Use ofaluminum also increases the likelihood of a failure of the movement armat the rear webbing and at the socket when exposed to high graspingforces. To mitigate the deformation, the thickness of the rear tabs wasincreased and the thickness of the front of the socket was alsoincreased.

With reference to FIGS. 31D-31E, the strain gauges 255 on the movementarm 232 are not only sensitive to axial loads produced while interactingwith an object at the tips, but are also sensitive to bending stress 257transferred from the force 258 applied to the instrument shaft 227 tothe movement arm 232. The movement arm 232 is preferably made ofaluminum 775. The strain gauge is calibrated for outputting force at thetip of the instrument. This output is compared against a force valuepre-determined to harm or damage tissue for a particular procedure. Suchinformation as to the appropriate use of force and level of respect fortissue is provided to the user as feedback at the end of the procedureas will be discussed later herein.

In addition to measuring the force applied by the user, a user's motionand instrument position may also be monitored in a mock surgicalprocedure or practice. Systems and methods for tracking instrumentposition and user movement while training with simulated organ modelsare provided. Feedback to the user is provided based on the collectedand analyzed data to assist in teaching and training the user. Variousand multiple surgical instruments and accessories, including but notlimited to graspers, dissectors, scissors, needle drivers, etc. can beemployed with the systems described herein for motion tracking. Datagathered from the sensorized surgical instruments can be used to comparean inexperienced trainee's performance to that of an experienced surgeonand provide appropriate feedback. The skills gained in this manner mayimprove the rate of skill acquisition of trainees and, as a result,improve surgical outcomes.

With reference to FIG. 32, a surgical simulator 10 is shown forlaparoscopic procedures that permit a trainee to practice intricatesurgical maneuvers in an environment that is safe and inexpensive. Thesimulator 10 generally consists of a cavity 12 comprising an illuminatedenvironment that can be accessed through surgical access devicescommonly referred to as trocars 412. The enclosure is sized andconfigured to replicate a surgical environment. For instance, thesimulator may appear to be an insufflated abdominal cavity and maycontain simulated organs 413 capable of being manipulated and “operatedon” using real surgical instruments 414, such as but not limited tograspers, dissectors, scissors and even energy based fusion and cuttingdevices. Additionally, the enclosure often makes use of an internalcamera 415 and external video monitor.

More advanced simulators may also make use of various sensors to recordthe user's performance and provide feedback. These advanced systems mayrecord a variety of parameters, herein referred to as metrics, includingbut not limited to motion path length, smoothness of motion, economy ofmovement, force, etc. The present invention is configured to track theuser's movements and the position of utilized instruments, interpret thecollected information and use it to improve user performance throughfeedback and appropriate teaching instructions. Different methods formonitoring and collecting motion and position data will be nowdescribed.

In reference to FIG. 33, a laparoscopic grasper 416 that includes aninertial motion unit (IMU) 417 consisting of a magnetometer, gyroscopeand accelerometer is shown. Data collected from the IMU 417, such asacceleration, angle, etc., is utilized to determine metrics such as, butnot limited to, motion smoothness, economy of motion and path length.This information is obtained by collecting the raw IMU data (such asacceleration, angular velocity, and azimuth) in real time and analyzingit on a connected computer.

After various data is collected from the one or more sensors describedabove, the data is processed to extract meaningful surgical laparoscopicskills assessment metrics for providing constructive user feedback. Userfeedback can be tailored to identify strengths and weaknesses withoutrelying on the subjective assistance of a third party. Users can viewtheir feedback after completing a module, task or procedure on thetraining system. Some examples of metrics that are computed forperformance feedback include but are not limited to (i) the total timeit takes for the procedure to be completed, (ii) the average smoothnessof motion of tool tips, (iii) the average economy of motion (i.e.efficiency), (iv) the average speed of motion at the tool tips, (v) theaverage work done, and (vi) the average energy efficiency at the tooltips.

A nine degree-of-freedom (DOF) inertial measurement unit (IMU) is usedas the means for motion tracking. The IMU consists of a combination ofsensors including an accelerometer, a magnetometer, and a gyroscope. Rawanalog voltage measurement is converted into raw digital values in unitspertinent to their specific sensor. The accelerometer measures theacceleration of the device on x, y, and z axis (in both positive andnegative directions) in reference to gravitational force converted intounits of acceleration (m/s²). The magnetometer measures the earth'smagnetic field in gauss units. The gyroscope measures the angularvelocity of the device about all three axes in radians per second(rad/s). A total of nine values are collected from the IMU per sample.For force measurement, 2 strain gauges are attached to a metal strutsituated within the grasper, which is primarily used to translate thegrasper actuation to the grasper tips. Each type of sensor is calibratedbefore data is collected. Samples are received approximately every 20milliseconds, saved into a database upstream, and passed into the dataanalysis utility. The data analysis utility includes datapre-processing, orientation analysis, and metrics analysis.

Once raw data has been collected and calibrated, data is pre-processed,and some preliminary analysis is performed before metrics arecalculated. The three reliable and well-tested metrics to measure auser's performance in simulators are (1) the time taken to complete thetask, (2) smoothness of motion, and (3) economy of motion. Data analysisalgorithms aim to quantify these metrics as will be detailedhereinbelow. Other metrics, such as average velocity of the tool tips,and energy efficiency will also be added into the analysis. Once metricscomputation is complete, the results are graphically conveyed to theuser for performance feedback. This overview of data processing andanalysis is illustrated in FIG. 34.

Before any type of analysis is done with the data, the data ispre-processed to ensure the data itself reflects as closely to the truevalue as possible. No two sensors are completely identical, and theirsignal responses will always present a slight margin of error due toinherent hardware variability. By calibrating the sensors, thedifference between the raw sensor signal output and the true value ischaracterized as a constant or a function depending on whether therelationship is linear or nonlinear. Each sensor will have a uniquecalibration constant or set of coefficients that are used to compensatefor errors in all the signals generated from each specific sensor. Forthis invention, there are a total of four types of sensors(accelerometer, magnetometer, gyroscope, strain gauge) that need to becalibrated, each requiring a different calibration method.

Turning now to FIG. 35, the accelerometer 501 is calibrated usinggravity as its reference. The IMU device is oriented with one of its 3axes perpendicular to the ground and held at that orientation before thesignal is recorded and averaged over a span of a few seconds. The sameis done on the opposite orientation (same axis). This is repeated forall three axes. A total of 6 gravity acceleration values are measured, 2for each x, y, and z axes. The average 518 of the two values will be theoffset for each axis.

Acc_(calibrated) _(_) _(x)=Acc_(raw) _(_) _(x)−(Acc_(x) _(_)_(positive)+Acc_(x) _(_) _(negative))*0.5

Acc_(calibrated) _(_) _(y)=Acc_(raw) _(_) _(y)−(Acc_(x) _(_)_(positive)+Acc_(x) _(_) _(negative))*0.5

Acc_(calibrated) _(_) _(z)=Acc_(raw) _(_) _(z)−(Acc_(x) _(_)_(positive)+Acc_(x) _(_) _(negative))*0.5

The magnetometer is calibrated using the earth's magnetic field as itsreference. Magnetic measurements will be subjected to distortions. Thesedistortions fall in one of two categories: hard or soft iron. Hard irondistortions are magnetic field offsets created by objects that are inthe same reference frame as the object of interest. If a piece offerrous or metallic material is physically attached to the samereferencing frame as the sensor, then this type of hard iron distortionwill cause a permanent bias in the sensor output. This bias is alsocaused by the electrical components, the PCB board, and the grasperhandle that the circuit board is mounted on. Soft iron distortions areconsidered deflections or alterations in the existing magnetic field.These distortions will stretch or distort the magnetic field dependingupon which direction the field acts relative to the sensor.

Referring now to FIG. 36, to calibrate the IMU, the IMU is oriented atas many angles and directions as possible to attain an even amount ofdata points to model a spherical representation of the earth's magneticfield. Once the raw magnetometer data 502 is recorded, it is fit into anellipsoid using a fitting algorithm. The ellipsoid center andcoefficients are calculated. The center values reflect the hard ironbias of the device, while the coefficients characterize the soft irondistortion (i.e. the shape of the distorted magnetic field surroundingthe device). Assuming that the earth's magnetic field is at the origin,and is perfectly spherical, the center offset and the transformationmatrix can be calculated as follows:

${Mag}_{center} = \begin{bmatrix}{m_{{center}\; \_ \; x},} & m_{{center}\; \_ \; y} & m_{{center}\; \_ \; z}\end{bmatrix}$ ${Mag}_{transform} = \begin{bmatrix}m_{xx} & m_{xy} & m_{xz} \\m_{yx} & m_{yy} & m_{yz} \\m_{zx} & m_{zy} & m_{zz}\end{bmatrix}$Mag_(calibrated) = (Mag_(raw) − Mag_(center)) × Mag_(transform)

The gyroscope measures angular acceleration, which means that when thedevice is perfectly still, a perfect gyroscope's signal output will be 0rad/s. To calibrate the gyroscope, the device is laid completely stillwhile raw gyroscope signals are recorded. A total of 3 values aremeasured and used to compensate for the error and noise.

Gyro_(calibrated)=Gyro_(raw)−Gyro_(atRest)

The strain gauges are calibrated using a load cell as a reference. Eachgrasper handle has two strain gauges placed on opposite sides of themetal strut as shown in FIG. 31B. The strut is loaded axially, and thestrain gauges are each interconnected to a Wheatstone bridge, whichmeasures the change in resistance of the strain gauges due to thecompression or elongation of the metal bar. Traditionally, a load cellcan be used to directly characterize the strain gauge signal in responseto load. The manner in which the bar is assembled into the handle isimportant because it can introduce complications that prevent accurateforce measurements using the load cell. One end of the metal bar isconnected to the actuator where the grasper is held, and the other endis connected to a rod that in turn actuates the grasper tips. Betweeneach end of the bar and their respective sites of actuation are manyjoining parts that work together to transfer force from the handle tothe grasper tips. These joining parts, in order to allow movement, aredesigned with clearance. When there is a change in direction of load(e.g. closing the grasper as soon as it has been opened), the separateparts will have to travel through this void before they make contactwith their adjacent parts again. This phenomenon causes different forcereadings on the same load applied in opposite directions (i.e.compression or tension), and is known as backlash. Calibration is doneby observing the difference in response of the strain gauge and the loadcell when the grasper is loaded (gripped), and when it is beingreleased. FIG. 37 shows that the strain gauge response will follow adifferent trend line when force is being loaded and when it is beingreleased due to backlash. An algorithm is written to automaticallyestimate the closest polynomial fits to both the upper 503 and lower 504trend lines, resulting in two sets of polynomial coefficients. Itseparates the two lines by first fitting all the data points to create asingle trend line that passes between the top and bottom trend lines ofinterest, which acts as a threshold line to separate data points thatbelong to the top line from those that belong to the bottom line. Itthen sweeps through the data over time and estimates whether the grasperis being loaded in one direction or the other. The algorithm thenapplies the corresponding polynomial coefficients to solve for trueforce being applied at the grasper tips.

To ensure analysis is as relevant to actual surgery as possible, boththe user's dominant and non-dominant hand movements are trackedsimultaneously. After each of the sensors is calibrated correctly, andprior to performing any analysis, time is one metric that can beobtained. Unfortunately, due to the nature of certain surgicalsimulation procedures, the user is occasionally required to put down thedevice mid-session. Since the length of time in which the device staysinactive in this form does not directly reflect on the skill of theuser, this idle factor is eliminated from the analysis in one variation.An algorithm to trim off these idle portions 505 is shown in FIG. 38. Itdoes so by sweeping through each of the axes of the accelerometer data,and calculating the derivative over time. When derivative is zero orclose to zero, it is assumed that there is no motion along that axis. Ifthe derivative remains to be zero or close to zero for more than 6seconds, it is considered to be set aside. A buffer 506 of approximately3 seconds is added to each of the ends of the idle start and end times505 to account for movements relating to the picking up or putting downof the device. The final start and end idle time is used as a referencefor downstream processing to identify the locations at which the data isto be segmented at. Useful data separated by intermediate idle regions,is segmented and stored into an array list separated by order 507 (i.e.a data set with 3 idle periods will have 4 data segments). Segments thatbelong to a single data set will be individually analyzed successively507 and be added to find total active time to complete the task. Thetotal active time to complete the task is when at least one of the toolsis not idle, and then the user is considered to be actively performingthe task. Once data has been segmented, and calibration has been appliedto the raw data, this information can be used to calculate orientationof the device over time. A sensor fusion algorithm that has beendeveloped to combine accelerometer, magnetometer, and gyroscopic data toestimate the orientation of the device over time is the Magnetic,Angular Rate, and Gravity (MARG) filter developed by Sebastian Madgwickillustrated in FIG. 39.

In order to understand how the algorithm is implemented, one must firstunderstand how each component in the IMU contributed to the overallestimation of orientation of the device. Since the gyroscope measuresangular velocity in all three axes, theoretically, these values can beintegrated to obtain angular displacement. Unfortunately, as with thecase for most sensors and discrete digital signals, integration andquantization error are almost always unavoidable. The result is thatthese small errors in the estimated displacement will quickly accumulateover time until the estimated orientation “drifts” significantly and nolonger estimates the orientation correctly. The accelerometer andmagnetometer is therefore present to provide reference for thegyroscope. Since the accelerometer measures acceleration along all threeaxis, it is also able to detect the direction gravity is pointedrelative to its own orientation. When the device is tilted slightly atan angle, the direction of gravity relative to the orientation of thedevice also tilts slightly at an angle identical but opposite thetilting motion. With some basic trigonometry, the roll and pitch of thedevice can be estimated. The roll and pitch are the angles at which thedevice is rotated about the axis on a plane parallel to the ground.There are several limitations to exclusively using the accelerometer toestimate orientation. Firstly, since accelerometers are also sensitiveto acceleration forces other than gravity, data is susceptible to errorif there is linear motion of the device. Secondly, yaw, which is theangle of rotation about the axis perpendicular to the ground, cannot beestimated since the direction of gravity with relation to orientation ofthe device will not change if the device is oriented north or east forexample. Yaw is, instead, estimated using the magnetometer. Themagnetometer is essentially a digital compass that provides informationabout the magnetic heading of the device, which can be converted intoyaw angles. The accelerometer and magnetometer estimations, whencombined with the gyroscope orientation estimations by an algorithm,acts as a filter that helps dampen the effects of integration errors inthe gyroscopes.

When dealing with orientations in algorithms, some common mathematicalrepresentations include Euler angles and the quaternion representation.Referring to FIG. 39, the MARG filter uses the quaternionrepresentation, and applies gradient-decent to optimize accelerometerand magnetometer data to the gyroscope data and estimate the measurementerror of the gyroscope as a quaternion derivative. Quaternion resultsare converted back into Euler angles 509 for more intuitivepost-processing of the orientation data.

Still referencing FIG. 39, the Euler angles (roll 510, pitch 511, andyaw 512) represent the angle traveled on the x, y, and z axesrespectively from the original orientation. Each Euler anglerepresentation can be converted to a unit vector notation thatrepresents orientation. Once the orientation vector is computed,analysis will proceed to metrics computation.

Total active time has already been estimated prior the beginning oforientation analysis. Other metrics to consider include economy ofmotion and smoothness. With reference to FIG. 41, the economy of motionmetric measures how well the user chooses the path of the tool tip tocomplete a specific procedure. In theory, the most optimal path is theshortest path possible to complete the procedure, and economy of motionis the ratio of the shortest, most efficient path to the measured pathlength of the user. In reality, the optimal path is very difficult toestimate as it depends largely on the type of procedure and the varyingapproaches that may exist even among the best of surgeons. To solve thisproblem, instead of estimating and comparing the measured path length tothe shortest path length, the measured path length 515 is compared tothe average path length of a pool of expert surgeons 516. Path length iscalculated, first, by taking the dot product of adjacent orientationvectors in the data sequence, which gives the angle of change inorientation. Each angle in the data sequence multiplied by the length ofthe tool gives the arc length that the tip traveled. The total pathlength is the sum of this series of arc lengths. The path lengthcalculated using this method is not the absolute path length, as thismethod assumes that there is no travel along the depth axis (i.e.grasper moving in and out axially through the trocar). The reason forthis limitation comes inherently from the IMU's inability to track 3Dposition. IMUs are only able to accurately track orientationinformation. The only means to estimate 3D position is throughintegrating the accelerometer data twice. Although this may be amathematically correct approach, in reality, accelerometers are verynoisy. Even after filtering, the noise will be amplified each time it isintegrated. Integrating each data point twice sequentially along thedata series allows for error to accumulate exponentially. In otherwords, three dimensional position tracking can only be achieved forseveral seconds before the estimation drifts far away from its true 3Dposition. Nevertheless, the ratio of the expert path length to the userpath length 517, though with an error, is assumed to be proportional tothe actual ratio using their true path lengths, and is used to measureeconomy of motion.

With reference to FIG. 40, smoothness measures the frequency andvariance of motion. It is assumed that expert data would typically showsmoother motion paths than less experienced surgeons. Factors that mayaffect smoothness of motion include hesitation, misjudgment of lateraland depth distance of tip to target, collision of the tool tips, andlack of speed and/or force control, all of which are more apparent innovices. To begin, the position of the tool tip is estimated. Asdescribed in the previous section, absolute 3D position tracking is notpossible while using an IMU. Instead, a pseudo-2D position is projectedby the lateral sweeping motion of a grasper pivoting at the entry point,and assumes that there is no movement in depth. This 2D positioncoordinate represents the path the tip travels. The curvature K of thepath over time is first calculated over time using the equation 513.Curvature gives a measure of the abruptness of change in path. Thesmoother the motion, the smaller the change from one curvature value tothe next. Smoothness can then be quantified statistically in relation tothe standard deviation of curvature change to mean of change 514. Thesmaller the resulting smoothness value, the less variability there is inmotion, the smoother the motion path, the more skilled the user.

Other smoothness algorithms that have been tested or considered includeone that applied the smoothness equation on each of the accelerometerdata series separately and took the average of all the smoothnessvalues; one that applied the smoothness values of each of the positioncoordinates and took the average of the resultant smoothness values; andone that performed an auto correlation of curvature. Auto-correlation isa way of calculating similarity of a signal with itself at an offsettime. This is useful to find whether there is a smooth transition fromone sample point to the next by offsetting by only a seconds time oreven a single data point by determining how similar the offset signal isto the original signal.

Other metrics that are explored include average velocity of tool tipsand energy efficiency. Average velocity is simply the distance travelledover time. Average velocity can be used in combination with othermetrics to gauge confidence and familiarity with the procedure. Pathlength from one sample to the next has already been computed whiledetermining the overall path length the tip of the tool travelled. Timeincrement between each sample increment is recorded in the raw data andcan be calculated by subtracting the previous time stamp from the mostcurrent time stamp along the sequential analysis. A velocity iscalculated between each sample increment and the average is taken.

Lastly, energy efficiency is computed using the force data collectedfrom the strain gauge. Force information is important in determining ifthe user is using excessive forces in accomplishing the task, and hence,causing unnecessary tissue damage. Due to the fact that each data setwas segmented, each of these algorithms are implemented to each segmentsequentially, yielding the same number of metrics as there are segmentsin the data set. These individual metrics are averaged to determine theoverall metric for that data set. Each individual device involved in thesimulation session will have computed metrics associated to it, andthese metrics will be combined for analysis overall.

The data is collected and analyzed via an interactive applicationinstalled on a computer or other microprocessing device. The applicationis present via a graphical user interface that is interactive offeringvarious learning modules such as on specific laparoscopic procedures andproviding user feedback on collected metrics from the sensorizedinstruments. The software application guides users through selecting alearning module and provides users with constructive feedback helpingusers increase surgical instrument handling skills and build manualdexterity.

The software can employ a variety of technologies, languages andframeworks to create an interactive software system. In particular,JavaFX® software platform, that has cross-platform support, can be usedto create the desktop application. JavaFX® applications are written inJava and can use Java® API libraries to access native systemcapabilities. JavaFX® also supports the use of cascading styling sheetsfor styling of the user interface. SQLite® software library can also beused in the present invention as a self-contained, serverless,transactional SQL database engine. This database engine is used tocreate and insert data pertaining to each learning module into adatabase, as well as data collected from the user to later be analyzed.Each screen of the application is populated with learning module datastored in the SQL database. The JavaFX® embedded browser WebKit® whichis an open source web browser engine may also be employed. This browsersupports most web browser technologies including HTML5, JavaScript®,Document Object Module, and Cascading Style Sheets. Each step of alaparoscopic procedure is displayed in an embedded web browser in thelearning module screen. The Data Driven Documents (D3) JavaScript®library may also be utilized to provide dynamic interactivevisualizations of data. D3 binds data to the web browser technology,Document Object Model, to which then D3 transformations can be applied.D3 visualizations using analyzed data collected during the learningmodule can then be displayed in an embedded browser in the feedbackscreen. The Webcam Capture Java® API can also be employed to captureimages from the connected laparoscope to display to the user. The livefeed from the laparoscope is embedded into the learning module screen.

With reference now to FIG. 42, the module devices screen page of theuser interface displays all of the connected devices 601. The graphicaluser interface includes virtual buttons displaying whether themagnetometers on each instrument have been calibrated. Selecting the“calibrate” button adjacent to each specific instrument will take theuser to the calibration screen page where magnetometer data from thatinstrument will be actively recorded and stored for calibration.

Turning to FIGS. 43A-43D, the device calibration screen page is shown.The calibration screen page displays the three steps 602 of themagnetometer calibration process 602. The steps 602 include orientationabout the three axes to obtain plot magnetometer data on XY, XZ, YZplanes. The application displays an animation that guides the userthrough the steps to properly calibrate the magnetometer for theirspecific sensor. In particular, the user is instructed by thecalibration screen to rotate the instrument. Once the application hascollected a sufficient amount of magnetometer data based on the numberof points plotted on a plane in a given number of quadrants, themagnetometer data is then stored in the database 630, to be used in theanalytics algorithms. The analytics algorithms correct for magnetometerbias due to encountering sources of magnetic field using an ellipsoidfit algorithm. The other sensors are also calibrated at step 600 of theflow chart shown in FIG. 49.

With reference now to FIGS. 44 and 49, in the next step 650 the type oftraining module is selected on the module selection screen page using avirtual button. This screen displays available learning modules for theuser to select. On the module selection screen 604, a selectable lesson603, for example, entitled “Total Laparoscopic Hysterectomy” isdisplayed and includes the title and short description of the learningmodule. The lesson module screen is populated by querying the SQLdatabase for stored learning modules titles and descriptions. Examplesof training modules include the following surgical procedures:laparoscopic cholecystectomy, laparoscopic right colectomy, and totallaparoscopic hysterectomy.

Turning to FIGS. 45 and 49, in the next step 652, after a learningmodule is selected on the module selection page 604, the module previewscreen page 614 that corresponds to the selected a learning module isdisplayed. The module learning objectives 605 and required instruments606 are included on the screen and displayed to the user. A previewvideo 607 of the selected module is also embedded into the screen page.Information for each part of the module preview screen is populated byquerying the SQL database for the selected module's description,objectives, required devices and preview video. For example, if alaparoscopic cholecystectomy module is selected, the video 607 at step652 will explain what a laparoscopic cholecystectomy is and itsadvantages over other non-laparoscopic procedures. The video willprovide a brief overview of major anatomical regions involved, and keytechniques and skills required to complete the procedure. The requiredinstruments 606 are displayed, for this example, to be four trocars, onegrasper, two dissectors, one scissor, and may further include one clipapplier and one optional retrieval bag. Step-by-step instructions areprovided via the imbedded video 607. Examples of other learning modulesinclude laparoscopic right colectomy, and total laparoscopichysterectomy.

Each practice module is configured to familiarize the practitioner withthe steps of the procedure and the relevant anatomy. It also permits theuser to practice the surgical technique and strive for proficiency incompleting the procedure safely and efficiently. To aid in trackingperformance, metrics measuring operative efficiency are also computedand displayed at the end of the procedure.

Turning to FIGS. 46 and 49, in the next step 654, a demographicsquestionnaire is presented to the user. Each question with theircorresponding set of answers is populated by querying the SQL database620 for the selected module's survey questions and answers 608. Theselected answer is then stored in a SQL database 630. Questions includeuser's title, level of experience, number of procedures performed,number of procedures assisted, and user's dominant hand.

With reference to FIGS. 47 and 49, in the next step 656, the learningmodule screen for the selected module is presented to the user. Withparticular reference to FIG. 47, the left side 609 of the graphical userinterface is an embedded video of a live laparoscope image feed of thecavity of the trainer displayed to the user. On the right side eachsurgical step 610 of the laparoscopic procedure is sequentiallydisplayed to user accompanied by a brief instruction of the surgicalstep and an embedded instructional video 611 showing an example of asuccessful performance of the step. Laparoscopic instruments being usedduring the learning module are shown on the bottom 612 of the livelaparoscope image feed. Data from laparoscopic instruments is streamedthrough serial ports and stored in the SQL database 630. For example, ifa laparoscopic cholecystectomy is selected as the learning module, thesurgical steps 610 that are displayed to the user include: (1) Firstentry: place your first port and survey the abdominal cavity forabnormalities and relevant anatomy; (2) Place ancillary ports: underdirect visualization, place your ancillary ports; (3) Retractgallbladder: position the patient with your grasper grasp the fundus ofthe gallbladder and retract cephalad and ipsilaterally to keep theregion of the cystic duct, cystic artery and common bile duct exposed;(4) Dissect the Triangle of Calot: with your grasper, grasp theinfundibulum of the gallbladder and retract inferio-laterally to exposeCalot's Triangle and use your dissector to bluntly dissect the triangleof Calot until the Critical View of Safety is achieved and only twostructures are visible entering the gallbladder; (5) Ligate and dividecystic duct and artery: ligate the cystic duct and artery by using yourclip applier to place three clips on each structure, two proximally andone distally, and use your scissors to divide the cystic duct and cysticartery; (6) Dissect gallbladder from liver bed: retract the gallbladderin the superio-lateral direction using your grasper holding theinfundibulum and scissors with or without electrosurgery; alternatively,a dedicated energy device may be used to carefully dissect thegallbladder entirely from the liver bed; (7) Specimen Extraction:Extract the specimen through one of your ports; and (8) Port Removal:survey the abdominal cavity one last time before removing your ports.

Turning now to FIGS. 48 and 49, in the next step 658 data that iscollected and stored during the learning module from the connectedlaparoscopic instruments is queried from the database 630, and runthrough analytics algorithms to output resulting metrics data. Resultingmetrics data from the analytics is then displayed to the user on thescreen 613 using D3 visualizations in a web browser embedded in thefeedback screen 613. As shown in FIG. 48, the user's time is displayedtogether with the average time and an expert's time to complete themodule providing comparative performance analysis to the user.Smoothness of motion and economy of motion are also displayed andcompared with the average and expert results. Based on the informationcollected in the survey at step 654, module results are categorizedaccordingly as expert or non-expert data. The results are averaged forexpert and non-experts and presented as shown.

It is understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplifications ofpreferred embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the present disclosure.

We claim:
 1. An instrument for surgical training comprising: a shaftassembly removably connected to a handle assembly; the handle assemblyincluding a movement arm having a distal end and a proximal end operablyconnected to a handle; the shaft assembly including a tool element at adistal end of the shaft assembly, a lumen, and a rod having a proximalend and a distal end connected to the tool element; the rod beingdisposed inside the lumen; the proximal end of the shaft assembly beingremovably connected to the handle assembly such that the proximal end ofthe rod is connected to the distal end of the movement arm; whereinactuation at the handle moves the movement arm and rod to operate thetool element; at least one sensor attached directly to the handleassembly and configured to acquire and transmit at least one relationaldata of the instrument with respect to a training environment during atraining procedure; and a computer system connected to the at least onesensor configured to receive, store and process the data and to outputat least one feedback to a user after the training procedure.
 2. Theinstrument of claim 1 wherein the at least one sensor includes a straingauge located on the movement arm.
 3. The instrument of claim 2 whereinthe strain gauge is configured to measure force applied by the user atthe tool element in relation to the training environment.
 4. Theinstrument of claim 1 wherein the at least one sensor includes anaccelerometer, gyroscope and magnetometer.
 5. The instrument of claim 1wherein the proximal end of the rod includes a ball end configured to beconnected with a spherical slot located at the distal end of themovement arm.
 6. The instrument of claim 1 wherein the tool element isconfigured as a scissor, grasper or dissector.
 7. The instrument ofclaim 1 wherein the training environment includes a laparoscopic trainerdefining an interior and at least one simulated tissue disposed in theinterior of the laparoscopic trainer.
 8. The instrument of claim 1wherein the at least one feedback is selected from the group consistingof a time to complete the training procedure by the user, a time tocomplete the training procedure by an expert, an average time tocomplete the training, an economy of motion of the user for the trainingprocedure, an economy of motion of an expert for the training procedure,an average economy of motion of all users for the training procedure; apath length of the instrument tip of an expert divided by a path lengthof the user for the training procedure; a path length of the instrumenttip of one or more expert users divided by an average path length of allusers for the training procedure; a smoothness of motion of the user forthe training procedure, a smoothness of motion of an expert for thetraining procedure, an average smoothness of motion of all users for thetraining procedure.
 9. The instrument of claim 1 wherein the at leastone feedback is a time to complete the training procedure by the user;the time to complete excluding idle time of the instrument.
 10. Theinstrument of claim 1 wherein the training procedure is selected by theuser from a plurality of pre-defined training procedures displayed onthe computer.
 11. A method for surgical training, comprising the stepsof: providing at least one surgical instrument having a handle assemblyconnected to an interchangeable shaft assembly; the surgical instrumentincluding a strain gauge, an accelerometer, a gyroscope and amagnetometer all directly attached to the handle assembly, operablyconnected to a computer, and configured to acquire at least one data;providing a laparoscopic trainer and at least one simulated tissuelocated inside the laparoscopic trainer; providing a group of predefinedsurgical procedures on the computer; selecting a predefined surgicalprocedure from the group of predefined surgical procedures; performingthe selected predefined surgical procedure by at least one user usingthe at least one surgical instrument upon the at least one simulatedtissue located inside the laparoscopic trainer; collecting data from oneor more of the strain gauge, accelerometer, gyroscope, and magnetometer;the data being related to the selected predefined surgical procedure;calculating at least one information from the data; providing on thecomputer the at least one information and/or data to the user uponcompletion of the selected predefined surgical procedure; the at leastone information and/or data being based on data collected for the atleast one user.
 12. The method for surgical training of claim 11 furtherincluding the step of providing a preview of the selected predefinedsurgical procedure to the user on the computer; the preview includingone or more of an introduction video, an exemplary video, a list ofsurgical instruments, and a list of learning objectives.
 13. The methodfor surgical training of claim 11 further including the step ofproviding on the computer a live video image of the predefined surgicalprocedure while being performed by the user
 14. The method for surgicaltraining of claim 13 wherein the step of providing a live video imageincludes sequentially providing each surgical step for performing theselected predefined surgical procedure on the same screen as the livevideo image.
 15. The method for surgical training of claim 11 whereinthe step of providing at least one information and/or data includesproviding a comparison of the at least one information and/or data forthe user upon completion of and related to the selected predefinedsurgical procedure and at least one other user.
 16. A laparoscopictrainer, comprising: a bottom; at least one sidewall encompassing thebottom; and a penetrable simulated abdominal wall defining at least aportion of a top; the top being spaced apart from the bottom to definean interior bounded by the at least one sidewall; wherein the at leastone sidewall includes a door configured to open and close to provideaccess to the interior; the door having an aperture extending from theoutside of the trainer to the interior to provide access to the interiorvia the aperture; and an interchangeable adapter extending between thetop and bottom and fixedly yet removably connected to the trainer in thelocation of the aperture.
 17. The laparoscopic trainer of claim 16wherein the adapter includes an aperture coincident with the aperture inthe door when the door is in a closed position; the adapter beingconfigured to mount a tubular simulated tissue structure having a lumenso as to provide access to an interior of the lumen of the simulatedtissue structure via the aperture in the door.
 18. The laparoscopictrainer of claim 16 wherein the adapter is sized and configured to blockthe aperture of the door and prevent light from entering the cavity. 19.The laparoscopic trainer of claim 16 further including a pair of railsfor slidably receiving and supporting an interchangeable tray having abase such that the base is spaced apart from the bottom of the trainer.20. The laparoscopic trainer of claim 16 further including feetconnected to and extending downwardly from the bottom of the trainer;the feet having a soft silicone composition to dampen the vibrations ofand/or self-level the trainer.